Method of bone fixation

ABSTRACT

Disclosed are devices and methods for stabilizing first and second bone portions relative to one another. In one example, implants, instruments and methods are provided that can be used with minimal exposure of the fractured bone and along curved path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/382,357, filed Dec. 16, 2016, entitled “Method of Bone Fixation”,which claims the benefit of U.S. Provisional Application No. 62/268,828,filed Dec. 17, 2015. U.S. patent application Ser. No. 15/382,357 is acontinuation-in-part of U.S. patent application Ser. No. 15/366,445,filed Dec. 1, 2016, which claims the benefit of U.S. ProvisionalApplication No. 62/266,009, filed Dec. 11, 2015. U.S. patent applicationSer. No. 15/382,357 is also a continuation-in-part of U.S. patentapplication Ser. No. 15/354,634, filed Nov. 17, 2016, now patented asU.S. Pat. No. 10,136,929 on Nov. 27, 2018, which is acontinuation-in-part of U.S. patent application Ser. No. 15/285,608,filed Oct. 5, 2016, now patented as U.S. Pat. No. 10,154,863 on Dec. 18,2018, which is a continuation-in-part of U.S. patent application Ser.No. 15/197,879, filed Jun. 30, 2016, which claims the benefit of U.S.Provisional Application No. 62/191,904, filed Jul. 13, 2015, and U.S.Provisional Application No. 62/238,780, filed Oct. 8, 2015. All of theabove applications are hereby incorporated by reference in theirentireties.

FIELD OF THE INVENTION

Examples of the invention relate generally to methods and devices forthe surgical treatment of bone and, more particularly, to thestabilization of bones with an intramedullary device.

BACKGROUND

Orthopedic medicine provides a wide array of implants that can beengaged with a bone such as for example to replace a portion of the boneor immobilize a fracture. It is common to utilize threaded components toengage the bone and to form a thread in a bone to receive the threadedcomponents. Prior art surgical instruments are limited to forming athread along straight paths in bones. However, it would be advantageousto form a thread along a curved path in a bone such as for example tomaximize the length of engagement with the bone or to follow a curvedportion of the bone such as for example an intramedullary canal. Thereis a need in the art for implants, instruments and methods that can beused with minimal exposure of the fractured bone and along curved paths.

SUMMARY

Examples of the invention provide devices and methods for stabilizingfirst and second bone portions relative to one another.

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples of the invention will be discussed with reference tothe appended drawings. These drawings depict only illustrative examplesof the invention and are not to be considered limiting of its scope.

FIG. 1 is a side elevation view of a screw according to one example ofthe invention;

FIG. 2 is a detail view of the screw of FIG. 1;

FIG. 3 is a detail view of the screw of FIG. 1;

FIG. 4 is an end view of the screw of FIG. 1;

FIGS. 5-7 are side views of a set of differently sized screws like thatof FIG. 1;

FIG. 8 is a perspective view of a screw according to one example of theinvention;

FIG. 9 is a top plan view of the screw of FIG. 8;

FIG. 10 is a side elevation view of the screw of FIG. 8;

FIG. 11 is an end view of the screw of FIG. 8;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 9; and

FIG. 13 is an exploded sectional view taken along line 12-12 of FIG. 9;

FIG. 14 is a cross sectional view of a bone implant according to oneexample of invention;

FIG. 15 is an exploded cross sectional view of the bone implant of FIG.14;

FIG. 16 is an exploded side view of a bone i r plant according to oneexample of the

FIG. 17 is an assembled sectional view taken along line 17-16 of FIG.16;

FIG. 18 is an exploded side view of a bone implant according to oneexample of the invention;

FIG. 19 is an assembled sectional view taken along line 19-19 of FIG.18;

FIG. 20 is an end view of the bone implant of FIG. 18;

FIG. 21 is a cross sectional view taken along line 21-21 of FIG. 19;

FIG. 22 is a top view of a bone implant according to one example of theinvention;

FIG. 23 is an end view of the bone implant of FIG. 22;

FIG. 24 is a front view of the bone implant of FIG. 22;

FIG. 25 is a cross sectional view taken along line 25-25 of FIG. 24;

FIGS. 26-28 are partial sectional views showing the insertion of thescrew of FIG. 1 into bone according to one example of the invention;

FIG. 29 is an exploded plan view of an example of an inserter instrumentuseable with the implants of FIGS. 1-28 according to one example of theinvention;

FIG. 30 is a perspective view of a handle of the inserter instrument ofFIG. 29;

FIG. 31 is a top view of the handle of FIG. 30;

FIG. 32 is a front view of the handle of FIG. 30;

FIG. 33 is a cross sectional view of the handle of FIG. 30 taken alongline 33-33 of FIG. 32;

FIG. 34 is a bottom view of the handle of FIG. 30;

FIG. 35 is an exploded perspective view of an inserter instrumentuseable with the implants of FIGS. 1-28 according to one example of theinvention;

FIG. 36 is a front view of a pair of nesting sleeves useable with theinserter instruments of FIGS. 29 and 35 according to one example of theinvention;

FIG. 37 is a front view of a drill wire useable in a method according toone example of the invention;

FIG. 38 is a front view of a depth gauge useable in a method accordingto one example of the invention;

FIG. 39 is a front view of a rigid drill useable in a method accordingto one example of the invention;

FIG. 40 is a front view of a flexible drill useable in a methodaccording to one example of the invention;

FIG. 41 is a perspective view of a centering guide useable in a methodaccording to one example of the invention;

FIG. 42 is a front view of the centering guide of FIG. 41;

FIG. 43 is a perspective view of a flexible tap according to one exampleof the invention;

FIG. 44 is a perspective view showing an alternative configuration ofthe shaft of the flexible tap of FIG. 43;

FIG. 45 is a detail view of a head of the flexible tap of FIG. 43;

FIG. 46 is an end view of the tap head of FIG. 45;

FIG. 47 is a detail view of an anchor feature of the flexible tap ofFIG. 43;

FIG. 48 is a plan view of the flexible tap of FIG. 43;

FIGS. 49 and 50 are partial sectional views of the flexible tap of FIG.43 illustrating relative motion of components of the tap;

FIGS. 51 and 52 are plan views illustrating a method of forming ahelical thread in a bone using the flexible tap of FIG. 43 according toone example of the invention;

FIGS. 53-72 are plan views illustrating a method of using the implantsand instruments of FIGS. 1-52 to fixate a fractured clavicle accordingto one example of the invention;

FIGS. 73-81 are perspective view illustrating a method fixating afractured fibula according to one example of the invention;

FIG. 82 is a plan view illustrating a method of fixating a fracturedradius according to one example of the invention; and

FIG. 83 is a perspective view illustrating a method fixating a fracturedfifth metatarsal according to one example of the invention.

DESCRIPTION OF THE ILLUSTRATIVE EXAMPLES

Examples of the invention relate generally to methods and devices forthe surgical treatment of bone and, more particularly, to thestabilization of bones with an intramedullary device. The term“transverse” is used herein to mean to cross at an angle; i.e. notparallel. The term includes, but is not limited to, right angles.

FIGS. 1-4 depict a bone implant 100 according to one example of theinvention having an elongate body 102 with a distal portion 104, amid-portion 106 and a proximal portion 108 spaced longitudinallyrelative to a longitudinal axis 110. The distal portion 104 includes ahelical thread 112 having a major diameter 114, a minor diameter 116,and a pitch 128. The mid-portion 106 has a non-threaded outer surface118 with an outer diameter 120. In the illustrative example of FIGS.1-4, the mid-portion outer diameter 120 is equal to or greater than thethread major diameter 114. The distal threaded portion 104 is operableto bend as it is threaded into a bone to follow a curved path. Forexample, the bending stiffness of the distal threaded portion 104 issuch that it will bend to follow a curved path in human bone. Such acurved path may be defined, for example, by a curved hole in the bone, aguide wire, or a natural bone feature such as a non-linearintramedullary canal bounded by cortical bone. This is distinct fromprior art threaded implants which if started on a curved path in humanbone would, when advanced, continue in a straight line and thus deviatefrom the curved path and form their own, straight, path through thebone. Preferably the bending stiffness of the threaded distal portion104 is lower than the bending stiffness of the mid-portion 106. Therelatively lower bending stiffness of the threaded distal portion 104causes the threaded distal portion to bend to follow a curved path whilethe relatively higher bending stiffness of the mid-portion causes themid-portion to remain straight to stabilize first and second boneportions relative to one another at a bone interface such as at afracture, osteotomy, or fusion site. The difference in bending stiffnessbetween the threaded distal portion 104 and the mid-portion 106 may beachieved in different ways. For example, the threaded distal portion 104and the mid-portion 106 may be made of different materials and/or mayhave different sectional moduli. In the illustrative example of FIGS.1-4, the threaded distal portion 104 and the mid-portion 106 havedifferent sectional moduli. The threaded distal portion minor diameter116 is less than the outer diameter 120 of the mid-portion 106 and thethreaded distal portion major diameter is less than or equal to theouter diameter 120 of the mid-portion 106. Preferably, the ratio of thebending stiffness of the mid-portion 106 to the bending stiffness of thethreaded distal portion 104 is in the range of 1.5:1 to 100:1. Morepreferably, the ratio is in the range of 2:1 to 20:1. For example,implants according to examples of the present invention and suitable forinternal fixation of a clavicle fracture and that fall within theseranges may have a major diameter 114 in the range of 4-6.5 mm, a minordiameter 116 in the range of 2.5-3.5 and a cannulation 101 with adiameter in the range of 1-2 mm. Preferably, the implant 100 is made, atleast in part, of a polymer.

Table 1 compares the calculated load required to bend a cantileveredtube of 3 mm outside diameter and 1.5 mm inside diameter around a radiusof 50 mm and an arc length of 26 mm for different materials. Thetitanium and stainless steel alloys are predicted to have a requiredload approximately 10 times that of the PEEK and PLLA. These loads wouldbe greater than the bone could withstand and a threaded device made ofthose materials would not follow a curved path in the bone but wouldinstead cause the bone to fail. In the case of the highly cold workedstainless steel, even if the bone could withstand the load, the implantwould fail since the minimum bend radius before failure of the implantis greater than 50 mm.

TABLE 1 Load at 50 mm bend radius Yield Failure Yield Failure FlexuralStress Stress Strain Strain Modulus Load Material (MPa) (MPa) (%) (%)(MPa) (N) PEEK 100 115 2.5% 20% 4 9.8 ASTM F2026 PLLA 90 100 2.6% 25%3.5 8.7 Ti—6Al—4V 880 990 0.8% 14% 114 91.7 ELI ASTM F136 316LVM 14681696 0.7% 3% 197 Not Stainless Steel possible ASTM F899

Another way to quantify the bending stiffness of the threaded distalportion 104 is by the amount of torque required to turn the threadeddistal portion 104 into a curved bone hole having a specified radius ofcurvature. For example, the threaded distal portion 104 preferablyrequires a torque less than 20 in-lbs to turn the distal threadedportion 104 into a bone to follow a curved path having a radius ofcurvature of 50 mm. More preferably the required torque is less than 10in-lbs. More preferably the required torque is less than 5 in-lbs. Morepreferably the required torque is approximately 2 in-lbs.

Table 2 compares the measured torque required to advance a threaded tube25 mm into a 50 mm threaded radius formed in a rigid test block. Thetubes were all machined to the same geometry but of different materials.The thread major diameter was 4.25 mm, the minor diameter was 3.0 mm andthe inner diameter of the tube was 1.5 mm. A rigid block was preparedhaving a curved, threaded path. Such a path has a pitch that is wider onthe outside of the curve and a pitch that is narrower on the inside ofthe curve corresponding to the shape of the thread when it is curved.Multiple samples of each tube were inserted into the block over an arclength of 25 mm. The maximum torque for each revolution was measured andit was found that the torque increased for each revolution. In Table 2,the range is the range of torque values from the first to the lastrevolution. The average is the average of the torque values for allrevolutions. The peak is the highest torque value and in all casesoccurred in the last revolution. However, the torque values for eachmaterial were relatively constant over the last few revolutions. Thetitanium and stainless steel alloys had measured torque valuesapproximately 10 times that of the PEEK. These tests were conductedusing a threaded block made of tool steel with a strength greater thanthat of the materials being tested in order to compare the torquevalues. As pointed out relative to Table 1, the loads generated from themetal implants would be greater than the bone could withstand and athreaded device as described herein made of these metals would notfollow a curved path in the bone but would instead cause the bone tofail.

TABLE 2 Torque to thread around rigid 50 mm radius Range Average PeakMaterial (in-lbs) (in-lbs) (in-lbs) PEEK    0-2.0 1.4 2.0 ASTM F2026Ti—6Al—4V ELI 0.7-25 16 25 ASTM F136 316LVM 0.5-20 13 20 Stainless SteelASTM F899

In addition to bending stiffness advantages, having the threaded distalportion major diameter less than or equal to the outer diameter 120 ofthe mid-portion 106 allows the distal threaded portion 104 to passthrough a passage in a bone that will be a sliding or press fit with themid-portion 106. A bone implant so configured, as shown in theillustrative example of FIGS. 1-4, can have an intramedullary canalfilling mid-portion 106 providing solid support to a bone interface anda relatively bendable distal threaded portion 104 following a curvedpath such as for threading into a distal portion of a curved bone tosecure the implant in the bone.

The proximal portion 108 may be identical to the mid-portion 106.Alternatively, the proximal portion may have a positive driverengagement feature (not shown) such as internal or external non-circularsurfaces, profiles, or holes. For example, an internal or externalslotted, threaded, triangular, square, hexagonal, hexalobular, or otherdrive feature may be provided. In addition, as shown in the illustrativeexample of FIGS. 1-4, the proximal portion 108 may include an optionalexternal helical thread 122 able to engage a bone portion to provideproximal fixation of the implant. For example, the proximal thread 122may have a major diameter 124, a minor diameter 126, and a pitch 130. Inthe illustrative example of FIGS. 1-4, the mid-portion outer diameter120 is equal to the proximal thread minor diameter 126 and the distalthread major diameter 114. The proximal portion may alternatively, or inaddition, receive a locking member such as a pin or screw transverse tothe longitudinal axis to lock a proximal bone portion to the nail. Thelocking member may be drilled through the proximal portion. Preferably,the proximal portion has one or more transverse holes formed through itfor receiving the locking member.

The distal and proximal thread pitches 128, 130 may advantageously bethe same or different depending on the application. For example, tostabilize a fracture, the implant 100 may be inserted into a bone acrossthe fracture so that the distal thread 112 is engaged with bone distalto the fracture and the proximal thread 122 is engaged with boneproximal to the fracture. If the bone portions on either side of thefracture are reduced to a desired final position prior to inserting theimplant 100, then it is advantageous for the thread pitches 128, 130 tobe equal so that insertion of the implant does not change the relativepositions of the bone portions. If on the other hand, it is desirable tomove the bone portions relative to one another by the action ofinserting the implant then it is advantageous for the pitches 128, 130to be different. For example, to move the bone portions closer togetherto reduce the fracture, the distal thread pitch 128 may be made greaterthan the proximal thread pitch 130 so that with the distal thread 112engaged distally and the proximal thread 122 engaged proximally, furtheradvancing the implant causes the distal bone portion to move proximallyrelative to the implant faster than the proximal bone portion movesproximally and thus move the bone portions closer together.Alternatively, to move the bone portions further apart to distract thefracture, the distal thread pitch 128 may be made smaller than theproximal thread pitch 130 so that with the distal thread 112 engageddistally and the proximal thread 122 engaged proximally, furtheradvancing the implant causes the distal bone portion to move proximallyrelative to the implant more slowly than the proximal bone portion movesproximally and thus move the bone portions further apart. Preferably,the bone implant 100 has a through passage, or cannulation 101, coaxialwith the longitudinal axis 110 to permit the bone implant 100 to beinserted over a guide wire.

The bone implant 100 of FIGS. 1-4, may advantageously be provided in aset containing a plurality of threaded implants as shown in theillustrative example of FIGS. 5-7. For example, it is advantageous in asurgical procedure to minimize the number of steps and the amount oftime needed to complete the procedure. In a bone fixation procedure, asurgeon often makes an initial sizing decision based on medical imaging.During the procedure, it may become expedient to change thepredetermined size based on observation of the surgical site or the fitof trial implants or instruments. For example, a surgeon may determineinitially that a smaller threaded implant is appropriate. However,during preparation of the site, the surgeon may determine that a largerthreaded will better grip the bone or fill, for example, a canal in thebone. The illustrative set of implants shown in FIGS. 5-7 facilitateschanging between sizes. Each implant thread 140, 150, 160 in the set hasa minor diameter 142, 152, 162, a major diameter 144, 154, 164, and apitch 146, 156, 166. The minor diameters 142, 152, 162 are equal to oneanother so that a single diameter drill will provide an initial borehole appropriate for all the threads in the set. The pitches 146, 156,166 are equal to one another so that all of the threads in the set willthreadably engage a helical thread of the same pitch. The majordiameters 144, 154, 164 may increase to provide progressively more bonepurchase or, for example, to span increasing larger intramedullarycanals. For example, with the set of implants of the illustrativeexample of FIGS. 5-7, a surgeon may drill a hole equal to the minordiameters 142, 152, 162 and then tap the hole with a tap correspondingto the thread of the smallest major diameter thread 140. The tactilefeedback received by the surgeon as the tap is inserted will indicate tothe surgeon if the thread major diameter is sufficient to provide adesired level of bone engagement. For example, the surgeon can feel ifthe tap is engaging the cortical walls of an intramedullary canal or ifthe tap is in softer cancellous bone. If the surgeon determines thatgreater engagement is desired, the surgeon can next tap the hole with atap corresponding to the thread of the next larger major diameter thread150. Since the minor diameters 142, 152, 162 and thread pitches 146,156, 166 are the same for all of the implants in the set, the next tapwill thread into the previously tapped hole and increase the bone threadmajor diameter without damaging the bone thread. Once the desired boneengagement is achieved, the surgeon may then insert the desired implant140, 150, 160. If in tapping the larger major diameter thread, thesurgeon determines that the bone is providing too much resistance, thesurgeon may revert to the smaller sized implant since the threads arestill compatible. Alternatively to using a separate tap, the screwthreads may be configured as self-tapping so that the implants may bethreaded directly into the bored hole.

In addition to the sizing advantages of having the same minor diameter142, 152, 162 across a family of implants, it is also advantageousbecause the distal threaded portion of each implant will have a similarbending stiffness to each of the other implants 140, 150, 160 since thecontinuous wall of the minor diameter contributes much more to thebending stiffness than the helical thread itself. This similar bendingstiffness means that they can be inserted around a similar bendingradius with a similar torque.

In the illustrative example of FIGS. 5-7, each implant 140, 150, 160 hasa mid-portion diameter 148, 158, 168 equal to the corresponding majordiameter 144, 154, 164. The increasing mid-portion diameters provideprogressively less flexible mid-portions across the set of implants and,for example, canal filling for increasingly larger bones if used in theintramedullary canal. If the implants incorporate the optionalincreasing mid-portion diameter as shown, then it is desirable tore-drill the mid-portion of the bone hole to accommodate the mid-portionwhen an increase in implant size is desired. However, the distal,threaded portion of the bone hole does not need to be re-drilled so theimplant threads will not be damaged by drilling. The mid-portiondiameter may also be larger than the corresponding distal thread majordiameter to further increase the mid-portion stiffness.

Alternatively to, or in addition to, the threaded distal portion 104 andmid-portion 106 having different sectional moduli, the threaded distalportion 104 and mid-portion 106 may have different material propertiessuch as two different materials or different conditions of the samematerial to produce a difference in bending stiffness between them.

In the illustrative example of FIGS. 8-13, an implant 170 has separatefirst and second members 172, 174 permanently joined together. The firstmember 172 includes an elongate body 176 with a proximal end 178, adistal end 180, a longitudinal axis 182, and an axial through passage184. The proximal end 178 of the first member includes a pair oftransverse through passages 181, 183. Each transverse passage 181, 183defines a longitudinal axis and the axes form an angle 185 between themabout the longitudinal axis 182 as best seen in FIG. 11. Providing morethan one transverse through passage increases options for attaching theimplant to bone fragments and options for fixation direction. Bothpassages may be used for fixation or the one that is most convenientlylocated may be used. Preferably the angle 185 is in the range of 0 to 90degrees. More preferably the angle 185 is in the range of 20 to 90degrees. In the illustrative example of FIGS. 8-13, the angle 185 is 45degrees. The proximal end 178 also includes opposed flats 187 forengaging a driver in torque transmitting relationship. An internalthread 189 within the passage 184 is engageable with, e.g., a threadeddraw bar to secure the first member to a driver.

The second member 174 includes an elongate body 186 with a proximal end188, a distal end 190, a longitudinal axis 192, an external helicalthread 194, and an axial through passage 196. The distal end 180 of thefirst member 172 and the proximal end 188 of the second member 174 mayhave complementary geometries to aid in joining them. In theillustrative example of FIGS. 8-13, the distal end 180 of the firstmember has a stepped conical taper and the proximal end 188 of thesecond member has a corresponding stepped conical socket 198. The matingsurfaces may be any suitable shape as determined by the materials andjoining technique including but not limited to plug and socket joints(as shown), scarf joints, butt joints, dovetail joints, finger joints,and lap joints. The joint may be reinforced with a third component suchas an adhesive, pin, or key. The joint may be formed by mechanicalinterlock, chemical bonding, molding, welding or other suitable joiningprocess. The final assembled implant 170, has a distal portion 191, amid-portion 193 and a proximal portion 195 and may have the threadforms, diameters and relationships as described relative to the examplesof FIGS. 1-7.

The first and second components 172, 174 may be made of differentmaterials or different conditions of the same material. For example,they may be made of polymers, metals, or ceramics. Metals may includestainless steel alloys, titanium, titanium alloys, cobalt-chromium steelalloys, nickel-titanium alloys, and/or others. Polymers may includenonresorbable polymers including polyolefins, polyesters, polyimides,polyamides, polyacrylates, poly(ketones), fluoropolymers, siloxane basedpolymers, and/or others. Polymers may include resorbable polymersincluding polyesters (e.g. lactide and glycolide), polyanhydrides,poly(aminoacid) polymers (e.g. tyrosine based polymers), and/or others.Other possible materials include nonresorbable and resorbable ceramics(e.g. hydroxyapatite and calcium sulfate) or biocompatible glasses. Theymay be made of homogenous materials or reinforced materials. They may bemade of crystallographically different materials such as annealed versuscold worked. It is preferable for the mid portion 193 and proximalportion 195 to have a higher bending stiffness than the distal portion191 and the distal portion preferably has a bending stiffness low enoughfor it to be inserted along a curved path in bone.

In a first example, the first component may be made of a metal with arelatively high degree of cold work and the second component of a metalwith a relatively low amount of cold work such as for example annealedand cold worked stainless steel. The components may be joined forexample by welding. However, as discussed relative to Table 1, mostmetals are far too stiff to allow threading along a curved path in abone within suitable torsional loads.

Preferably the distal portion is made of a polymer. In a second example,the first component is made of a metal, such as stainless steel or atitanium alloy, and the second component is made of a polymer such aspolyetheretherketone (PEEK) or a polylactide polymer (e.g. PLLA). Thecomponents may be joined such as for example by threading them together.

Preferably both components are made of polymers. In a third example, thefirst and second components are both made of non-resorbable polymers.For example, the first component may be made of fiber reinforced PEEK(e.g. Invibio PEEK-Optima™ Ultra-Reinforced) and the second componentmay be made of neat (unreinforced) PEEK (e.g. Invibio PEEK-Optima™Natural). The fiber reinforced PEEK is strong while the neat PEEK isrelatively flexible allowing it to be easily threaded around a curvedpath even while having a relatively large bone filling diameter. Thecomponents may be joined, e.g. by molding the components as a continuousmatrix with first component fiber reinforcement and second componentneat polymer with polymer chains extending across the joint interface.In the illustrative example of FIGS. 8-13, the second component isrelatively more transparent to laser radiation than the first componentand the parts are joined by laser welding at the conical interface. Thelaser energy passes relatively easily through the second component andis absorbed by the first component so that localized heating at theconical interface takes place causing the polymer constituent of the twocomponents to fuse together.

In a fourth example, the first and second components are made ofresorbable polymers. For example, the mid-portion may be made of a glassfiber reinforced PLLA (e.g. Corbion-Purac FiberLive™) and the distalportion may be made of neat PLLA.

Alternatively, the first member 172 and second member 174 may form onecontinuous part with different properties between first and secondportions. The difference in properties may be achieved, for example, bydifferent processing (e.g. thermal processing) or blending materials.For example, different polymers may be combined in a single injectionmold cavity and formed together. The polymers may be blended so thatthere is a transition between them. In another example, stiffeningand/or strengthening material, e.g. fibers, whiskers, and/or granules,may be selectively incorporated in, e.g., the first portion.

FIGS. 14 and 15 illustrate an example of an implant 270 similar to thatof FIGS. 8-13 except that the first member 272 is not cannulated, thefirst member 272 extends the full length of the second member 274, andthe transverse holes 281, 283 are coplanar. The implant 270 may beassembled as with the prior example including by using complimentaryscrew threads in the proximal region of the second member 274 and midportion of the first member 272 as indicated by reference number 250.The implant 270 of the example of FIGS. 14 and 15 may be include any ofthe materials and features described relative to the prior examples. If,for example, the first member 272 is made of a radiographically moreopaque material than the second member 274, then the first member willprovide a radiographic marker over the entire length of the screw 270that may be radiographically visualized during and after surgery toconfirm implant placement. For example, a metal first component andpolymer second component would provide for radiographic visualization ofthe metal first component. It has been found by the present inventorsthat the bending stiffness of the distal end of the implant is notmaterially changed by eliminating the axial through passage of the firstcomponent and is essentially unchanged when the bending stiffness of aguide wire is accounted for which was optionally used with the previouscannulated implant examples. The guide wire is not necessary inasmuch asthe implant 270 will follow a curved path receiving it. The transverseholes 181, 183 may be provided in any number or not at all as desiredbut it has been found that one is sufficient and two provides the userwith additional fixation choice.

FIGS. 16 and 17 illustrate a bone implant 400 useful for stabilizingbone fractures according to one example of the invention. The boneimplant 400 includes a body 402 defining a longitudinal axis 404extending between a proximal end 406 and a distal end 408. The body hasan elongate distal portion 410 having an outer surface 412 defining ascrew thread 414 having a minor diameter 416 and a major diameter 418.The body has an elongate proximal portion 430 having a non-threadedouter surface 432. Passages 434 and 436 are each formed through theproximal portion 430 transverse to the longitudinal axis from a firstopening 438, 440 on the surface of the proximal portion to a secondopening 442, 444 on the surface of the proximal portion. A driverengaging feature is formed at the proximal end for engaging a driver intorque transmitting relationship. The driver engaging feature may be amale feature or a female feature. Preferably it is a polygonal featureengageable with a correspondingly shaped driver. In the example of FIGS.16 and 17, the driver engaging feature is a hexagonal socket 446 formedin the proximal end of the implant. The socket 446 includes a threadedrecess 448 for threaded engagement with other tools such as a driverretaining draw rod, a cross pinning guide, or the like. As with all ofthe examples herein, the distal portion is responsive to rotation of theimplant to thread into a bone and advance the bone implant into thebone. This rotary advancement action is advantageous compared to typicalbone nails that are impacted into the bone since the threadedadvancement is less stressful to the bone and surrounding tissues. Asthe distal portion is threaded into the bone, it pulls the proximalportion into the bone. The distal threaded portion is anchored in thebone by the thread 414. The smooth proximal portion may be positioned tospan a fracture so that, for example, no sharp edges are engaged withthe fracture and no stress concentrating features that might weaken theimplant span the fracture.

In the example of FIGS. 16 and 17, the proximal portion has a length 450measured from the free proximal end 406 to the proximal start 452 of thethreads of the distal portion. The proximal portion has a maximumdiameter. For example, for a conical or cylindrical proximal portion themaximum diameter is simply the largest diameter along the proximalportion. For an ovoid proximal portion, the maximum diameter would bethe major diameter of the elliptical cross section. For other shapes,such as fluted proximal portions, the maximum diameter is the maximumdimension normal to the longitudinal axis 404 of the proximal portion.The maximum diameter is preferably constant over a portion of theproximal portion length to provide a uniform thickness for spanning afracture. For example, the maximum diameter is preferably uniform overat least one-fourth of the proximal portion length; more preferably atleast one-third; more preferably at least one-half; more preferably morethan one-half. In the illustrative example of FIGS. 16 and 17, theproximal portion has a constant cylindrical diameter over its entirelength. The driver engaging feature preferably has a maximum dimensionnormal to the longitudinal axis that is less than or equal to themaximum diameter of the proximal portion so that, for example, theproximal end of the bone implant may be seated below the bone surface.

The bone implant may be a unitary construct, like shown in theillustrative example of FIGS. 1-4, in which the proximal and distalportions are formed of one continuous material. Optionally, the proximaland distal portions may be separate components joined together as shownin the example of FIG. 8 and the example of FIG. 14. In the illustrativeexample of FIGS. 16 and 17, the bone implant includes a sleeve 460surrounding a separate core 462. The sleeve and core are joined togetherto form the body. Various methods may be used to join the sleeve andcore. For example, they may be threaded, pinned, bonded, welded, orotherwise joined. In the example of FIGS. 16 and 17, the sleeve isthreaded onto the core via an internal thread 464 and corresponding malethread 466 formed on the core. The sleeve is further pinned to the corewith a pin 468 pressed through holes 470, 472 in the sleeve wall and inthe core.

As described relative to previous examples, it is desirable for thedistal portion to have a lower bending resistance than the proximalportion. In one example, the sleeve is at least partially formed of apolymer and the core is at least partially formed of a metal. In theexample of FIGS. 16 and 17, the sleeve is formed from a polymer andincludes the distal screw thread while the core is formed from a metaland includes the proximal portion. In one example, the core is made of abiocompatible titanium alloy and the sleeve is made of a biocompatiblepoly(ketone) polymer such as, for example, polyetheretherketone. Inanother example, the core is made of a suitable biocompatible metal andthe sleeve is made of a resorbable polymer so that, over time, thesleeve will resorb in the patient's body and allow gradually increasingmotion of the bone and load transfer to the bone to promote healing. Thecore may extend partway toward the distal end as in the example of FIG.8, all the way to the distal end as in the example of FIG. 14, or it mayextend past the distal end as in the example of FIG. 16. With the tip480 of the core extending beyond the distal end, the tip 480 provides aneasier start of the implant into a hole in the bone and, as shown in theexample of FIGS. 16 and 17, the tip 480 provides a smooth bearingsurface for following a curved path in a bone.

FIGS. 18 through 21 illustrate a bone implant 500 similar to that ofFIGS. 16 and 17. The bone implant 500 includes a core 502 and a sleeve504. In the example of FIGS. 18 through 21, the smooth proximal portion506 is more evenly proportioned over the core and sleeve. Also, the coresteps up more gradually in diameter from the distal end 508 to theproximal end 510 resulting in a more gradual transition in bendingstiffness over three zones. In a first zone 512, a relatively thinportion of the core is surrounded by a relatively thick portion of thesleeve. In a second zone 514, a relatively thicker portion of the coreis surrounded by a relatively thinner portion of the sleeve. In a thirdzone 516, only a relatively thicker portion of the core remains. Also,in the example of FIGS. 18 through 21 a slip resisting feature isprovided on the core and a polymer sleeve is molded to the core so thatthe polymer and slip resisting feature interdigitate. The slip resistingfeature may be knurling, threads, grooves, splines, spikes, holes, orother features. The slip resisting feature may be oriented to enhancetorque transfer, longitudinal force transfer, or otherwise oriented. Inthe example of FIGS. 18 through 21, the slip resisting feature includeslongitudinal splines 518 to enhance the ability to transfer torquebetween the core and sleeve. Longitudinal force transfer is sufficientlyaccommodated by the bonding of the sleeve to the core during the moldingprocess. The proximal end 510 includes an hexalobular socket 511 forengaging a driver.

In use, the preceding implants may be provided in an appropriate sizeand inserted into a bone to span a fracture in the bone. Preferably theproximal portion of the implant spans the fracture. The arrangement of asmooth proximal portion and a threaded distal portion permits rotatingthe bone implant to cause the threaded distal portion to engage the boneand pull the proximal portion of the bone implant into a positioningspanning the fracture. In the case of an implant comprising a resorbablepolymer, the polymer will resorb over time in the patient to graduallytransfer load to and permit motion of the bone to enhance healing of thefracture. One or more pins or screws may be inserted so that they extendthrough one or more of the passages in the proximal end and through aportion of the bone to fix the bone to the proximal portion of theimplant. For example, with the distal end of the bone implant fixed byengagement of the distal threads in a distal portion of the bone aproximal portion of the bone may be secured with pins or screws asdescribed. This may be used to hold compression or distraction on boneportions on opposing sides of the fracture or to attach loose bonefragments.

FIGS. 22-25 illustrate a bone implant 600 similar to the precedingexamples inasmuch as it has a smooth rod-like proximal portion 602 and athreaded distal portion 604. The proximal portion 602 has one or moretransverse passages through the proximal portion, each passage extendingfrom a first opening on the surface of the proximal portion to a secondopening on the surface of the proximal portion. The distal portion maybe threaded into a bone to secure the implant 600 to the bone at thedistal end. The proximal portion is preferably positioned to bridge afracture to provide support to the fracture while the fracture heals.The transverse passages can receive a fastener such as a pin, wire,screw or the like to connect the proximal portion to bone. In theillustrative example of FIGS. 22-25, the implant 600 is configured forplacement in the intramedullary canal of a fibular bone to support afracture of the fibular bone and optionally to support screws forreinforcing the syndesmosis joint of an ankle. The proximal portionincludes a first pair of holes 606 perpendicular to the implantlongitudinal axis 608 and angled relative to one another about the axis608. The first pair of holes 606 is positioned nearer the proximal end610 of the implant to receive fasteners for attaching the implant 600 toa portion of the bone, or fragment, proximal to a fracture. The implantfurther includes a second pair of holes 612 perpendicular to the implantlongitudinal axis and, in this example, parallel to one another. Thesecond pair of holes 612 is positioned distal to the first pair and isarranged to receive fasteners that extend through the fibula and intothe tibia to reinforce the syndesmosis joint. In the illustrativeexample of FIGS. 22-25 the implant 600 is a unitary construction. Inother embodiments, the implant 600 may include a greater or a lessernumber of transverse holes or no holes at all. The transverse holes maybe perpendicular to the axis 608 as shown or at any other angle suitablefor the target anatomy. The implant may be made of two or more partsjoined together as in the previous examples. The distal portion 604includes a distal thread 620 having a major diameter 622, a minordiameter 624, and a pitch 626.

The various examples according to the invention have a decreased bendingstiffness of the distal portion relative to the proximal portion usingvarious strategies including different section moduli and differentmaterials. It is desirable for the distal thread to have a lower bendingstiffness than conventional bone screws of a similar major diameter. Inthe illustrative examples, the bending stiffness of the distal portionmay be lowered by utilizing a novel screw thread. For example, a threadaccording to an example of the invention has a smaller minor diameterand/or a larger pitch than a conventional bone screw thread. Table 3compares illustrative examples of screw thread geometry according toexamples of the invention to the industry standard bone screw threadsdescribed in ASTM F543.

TABLE 3 Screw thread geometry - Dimensions in mm B C D E Maj. Maj. Min.Min. A dia. dia. dia. dia. F B/E C/D B/F C/F D/F E/F Thread max min maxmin Pitch ratio ratio ratio ratio ratio ratio ASTM HA 1.5 1.50 1.35 1.101.00 0.50 1.50 1.23 3.00 2.70 2.20 2.00 ASTM HA 2.0 2.00 1.85 1.30 1.200.60 1.67 1.42 3.33 3.08 2.17 2.00 ASTM HA 2.7 2.70 2.55 1.90 1.75 1.001.54 1.34 2.70 2.55 1.90 1.75 ASTM HA 3.5 3.50 3.35 2.40 2.25 1.25 1.561.40 2.80 2.68 1.92 1.80 ASTM HA 4.0 4.00 3.85 2.90 2.75 1.50 1.45 1.332.67 2.57 1.93 1.83 ASTM HA 4.5 4.50 4.35 3.00 2.85 1.75 1.58 1.45 2.572.49 1.71 1.63 ASTM HA 5.0 5.00 4.85 3.50 3.35 1.75 1.49 1.39 2.86 2.772.00 1.91 ASTM HB 4.0 4.00 3.85 1.90 1.75 1.75 2.29 2.03 2.29 2.20 1.091.00 ASTM HB 6.5 6.50 6.35 3.00 2.85 2.75 2.28 2.12 2.36 2.31 1.09 1.04ASTM HC 2.9 2.90 2.79 2.18 2.03 1.06 1.43 1.28 2.74 2.63 2.06 1.92 ASTMHC 3.5 3.53 3.43 2.64 2.51 1.27 1.41 1.30 2.78 2.70 2.08 1.98 ASTM HC3.9 3.91 3.78 2.92 2.77 1.27 1.41 1.29 3.08 2.98 2.30 2.18 ASTM HC 4.24.22 4.09 3.25 2.95 1.27 1.43 1.26 3.32 3.22 2.56 2.32 ASTM HD 4.0 4.033.97 2.95 2.89 1.59 1.39 1.35 2.53 2.50 1.86 1.82 ASTM HD 4.5 4.53 4.472.95 2.89 2.18 1.57 1.52 2.08 2.05 1.35 1.33 Example 1 3.55 3.45 2.051.95 2.75 1.82 1.68 1.29 1.25 0.75 0.71 Example 2 3.25 3.10 1.50 1.352.25 2.41 2.07 1.44 1.38 0.67 0.60 Example 3 5.25 5.10 3.00 2.85 2.751.84 1.70 1.91 1.85 1.09 1.04

Column A is a description of each of the threads being compared. ASTMType HA threads correspond to the standard for bone screws having aspherical undersurface head, a shallow asymmetrical buttress thread, anda deep screw head. ASTM Type HB threads correspond to the standard forbone screws having a spherical undersurface head, a deep asymmetricalbuttress thread, and a shallow screw head. ASTM Type HC threadscorrespond to the standard for bone screws having a conical undersurfacehead and a symmetrical thread. ASTM Type HD threads correspond to thestandard for bone screws having a conical undersurface head and anasymmetrical thread. Column B is the maximum major diameter for thethread including permitted manufacturing tolerances. Column C is theminimum major diameter for the thread including permitted manufacturingtolerances. Column D is the maximum minor diameter for the threadincluding permitted manufacturing tolerances. Column E is the minimumminor diameter for the thread including permitted manufacturingtolerances. Column F is the thread pitch. Column B/E is the ratio of themaximum major diameter to the minimum minor diameter and represents thelargest major diameter to minor diameter ratio for the thread. ColumnC/D is the ratio of the minimum major diameter to the maximum minordiameter and represents the smallest major diameter to minor diameterratio for the thread. Column B/F is the ratio of the maximum majordiameter to the pitch and represents the largest major diameter to pitchratio for the thread. Column C/F is the ratio of the minimum majordiameter to the pitch and represents the smallest major diameter topitch ratio for the thread. Column D/F is the ratio of the maximum minordiameter to pitch and represents the largest minor diameter to pitchratio for the thread. Column E/F is the ratio of the minimum minordiameter to pitch and represents the smallest minor diameter to pitchratio for the thread.

Referring to columns B/E and C/D, standard bone screws with a threadmajor diameter less than 4.0 mm have a major diameter to minor diameterratio less than 1.7.

Referring to column F of Table 3, standard bone screws with a threadmajor diameter less than 6.5 mm have a pitch less than 2.2 mm. Standardbone screws with a thread major diameter less than 4.5 mm have a pitchequal to or less than 1.75 mm. Standard bone screws with a thread majordiameter less than 4.0 mm have a pitch less than 1.5 mm. Looking at itanother way, referring to columns B/F and C/F, standard bone screws havea major diameter to pitch ratio greater than 2. Standard bone screwswith a thread major diameter less than 4.0 mm have a major diameter topitch ratio greater than 2.5. Referring to columns D/F and E/F, standardbone screws have a minor diameter to pitch ratio greater than or equalto 1. Standard bone screws with a thread major diameter less than 4.0 mmhave a minor diameter to pitch ratio greater than or equal to 1.75.

Examples of the invention have a thread with a smaller minor diameterand/or a larger pitch than standard bone screws of a similar size to,for example, enable the screw thread to bend to follow a curved path ina bone.

Referring to Example 1 according to the invention, the example threadhas a 3.5 mm nominal major diameter, a 2.00 mm nominal minor diameter, apitch of 2.75 mm, a major diameter to minor diameter ratio between 1.68and 1.82, a major diameter to pitch ratio between 1.25 and 1.29, and aminor diameter to pitch ratio between 0.71 and 0.75. Comparing Example 1to ASTM HA 3.5 and ASTM HC 3.5, it is seen that the thread of Example 1has a minor diameter approximately 15-20% smaller than similar sizedstandard bone screws. In addition, the thread of Example 1 has a pitchmore than double the length of similar sized standard bone screws. Themajor diameter to minor diameter ratio for the thread of Example 1 isapproximately 20-30% greater than for similar sized bone screws. Themajor diameter to pitch ratio for the thread of Example 1 is less than50% that of similarly sized standard screws and the minor diameter topitch ratio for the thread of Example 1 is less than 40% that ofsimilarly sized standard bone screws. With its unconventional decreasedminor diameter and increased thread pitch, a thread according to Example1 made of Ti-6A1-4V has been shown by the present inventors to be ableto bend to follow the natural curve of the intramedullary canal of ahuman fibula.

Referring to Example 2 according to the invention, the example threadhas a 3.18 mm nominal major diameter, a 1.43 mm nominal minor diameter,a pitch of 2.25 mm, a major diameter to minor diameter ratio between2.07 and 2.41, a major diameter to pitch ratio between 1.38 and 1.44,and a minor diameter to pitch ratio between 0.60 and 0.67. Comparingexample 2 to ASTM HA 3.5 and ASTM HC 2.9, the most similar sizedstandard bone screw threads, it is seen that the thread of Example 2 hasa minor diameter approximately 30-40% smaller than similar sizedstandard bone screws. In fact, the thread of Example 2 has a minordiameter smaller than an ASTM HA 2.7 thread and most closely resemblesthat of the much smaller ASTM HA 2.0 thread. In addition, the thread ofExample 2 has a pitch more than double that of similar sized standardbone screws. The major diameter to minor diameter ratio for the threadof Example 2 is approximately 50-65% greater than for similar sized bonescrews. The major diameter to pitch ratio for the thread of Example 2 isapproximately 50% that of similarly sized standard screws and the minordiameter to pitch ratio for the thread of Example 2 is less than 35%that of similarly sized standard bone screws. With its unconventionaldecreased minor diameter and increased thread pitch, a thread accordingto Example 2 made of polyetheretherketone has been shown by the presentinventors to be able to bend to follow the natural curve of theintramedullary canal of a human clavicle.

Referring to Example 3 according to the invention, the example threadhas a 5.18 mm nominal major diameter, a 2.93 mm nominal minor diameter,a pitch of 2.75 mm, a major diameter to minor diameter ratio between1.70 and 1.84, a major diameter to pitch ratio between 1.85 and 1.91,and a minor diameter to pitch ratio between 1.04 and 1.09. Comparingexample 3 to ASTM HA 5.0, the most similar sized standard bone screwthread, it is seen that the thread of Example 3 has a minor diameterapproximately 15% smaller than similar sized standard bone screws. Inaddition, the thread of Example 3 has a pitch approximately 60% greaterthan similar sized standard bone screws. The major diameter to minordiameter ratio for the thread of Example 3 is approximately 23% greaterthan for similar sized bone screws. The major diameter to pitch ratiofor the thread of Example 3 is approximately 67% that of similarly sizedstandard screws and the minor diameter to pitch ratio for the thread ofExample 3 is less than 55% that of similarly sized standard bone screws.With its unconventional decreased minor diameter and increased threadpitch, a thread according to Example 3 made of polyetheretherketone hasbeen shown by the present inventors to be able to bend to follow thenatural curve of the intramedullary canal of a human clavicle.

Examples of threads according to the invention preferably have a pitchgreater than that for standard bone screws of a similar major diameter.For example, for threads with a major diameter less than 6.25 mm, it ispreferable to have a pitch greater than 2.2 mm; more preferably greaterthan 2.5; more preferably greater than or equal to 2.75. For threadswith a major diameter less than 4.0 mm, it is preferable to have a pitchgreater than 1.5 mm; more preferably greater than 1.75; more preferablygreater than 2.0; more preferably greater than 2.25; more preferablygreater than or equal to 2.75.

Examples of threads according to the invention having a major diameterless than 4.0 mm preferably have a major diameter to minor diameterratio greater than 1.7; more preferably greater than 1.8; morepreferably greater than 1.9; more preferably greater than 2.0.

Examples of threads according to the invention preferably have a majordiameter to pitch ratio less than 2; more preferably less than 1.75;more preferably less than 1.5; more preferably less than 1.4; morepreferably less than 1.3. For threads having a major diameter less than4.0 mm, the major diameter to pitch ratio is preferably less than 2.7;more preferably less than 2.5; more preferably less than 2.25.

Examples of threads according to the invention preferably have a minordiameter to pitch ratio less than 1.2; more preferably less than 1.0;more preferably less than 0.8; more preferably less than or equal to0.75, more preferably less than 0.7.

FIGS. 26-28 illustrate an implant being inserted into first and secondbone portions 200, 202 having a bone interface 204 between them. Theimplant could be according to any of the preceding examples and thevariations described herein. In the particular example of FIGS. 26-28,the example of FIG. 1 is shown. A first or proximal bore 206 is formedin the first bone portion 200, across the bone interface 204, and intothe second bone portion 202. A second or distal bore 208 extendsdistally from the proximal bore 206 defining a curved path 210. Theimplant 100 is advanced through the proximal bore 206 until the distalthreads engage the distal bore 208 as shown in FIG. 27. Furtheradvancing the implant 100 causes it to bend to follow the curved path210 as shown in FIG. 28. Having a straight portion of the path, and thusthe straight mid portion of the implant 100, spanning the bone interfaceresults in a zero stress and strain state at the bone interface whichprevents separation of the bone portions 200, 202 at the interface 204.

FIGS. 29-34 depict an illustrative example of an inserter 1400 useablewith the flexible implant 170 of FIGS. 8-13. The inserter 1400 is amodular design including an elongated, cannulated, coupling member 1402having a proximal end 1404, a distal end 1406 and a longitudinal axis1408 extending between the proximal and distal ends 1404, 1406. A hub1410 coaxial with the longitudinal axis 1408 is formed intermediate theproximal and distal ends 1404, 1406. The hub includes a proximal facingshoulder 1412 and a distal facing shoulder 1414. A post 1416 extendsproximally from the hub to the proximal end 1404 and includes a radialboss 1418 that tapers proximally and forms a shoulder 1420 distally. Ashaft 1422 extends distally from the hub 1410 to the distal end 1406 andincludes an engagement feature operable to engage the proximal end of animplant in torque transmitting relationship. For example, the engagementfeature may include a pair of opposed tongues 1424 engageable with theopposed flats 187 of the implant 170. The hub 1410 includes a thread1426 distal to the distal shoulder 1414. The hub includes an alignmentmark in the form of an alignment notch 1428 oriented parallel to thelongitudinal axis 1408. A flat 1429 is formed on the hub 1410. Acannulated draw bar 1480 is coaxially receivable in the coupling member1402 with a hex head 1482 abutting the proximal end of the post 1416 anda distal end 1484 extending to the distal end of the shaft 1422. Thedistal end 1484 of the draw bar includes a thread 1486 engageable withthe thread 189 in the passage 184 of the implant 170 to secure theimplant 170 to the coupling member 1402.

A handle assembly 1430 is removably engageable with the proximal portionof the coupling member 1402. The handle assembly includes a cannulatedhandle 1432 and a cap 1434 threadably engageable with the handle 1432.The handle is shown in detail in FIGS. 30-34. The handle 1432 includes acylindrical body 1436 having a “D”-shaped distal opening 1438. The flatside of the opening is engageable with the flat 1429 on the hub to alignthe handle in a predetermined orientation relative to the hub 1410 andthe engagement feature of the shaft 1422. A boss 1440 protrudes from thedistal end of the handle to engage a hole (not shown) formed in theproximal shoulder 1412 of the hub. A button 1442 is mounted in thehandle 1432 for transverse translation between first and secondpositions. The button has an opening through it having an inner profile1444 with a wider portion 1446 and a narrower portion 1448. The buttonis biased by a spring 1450 toward a first position in which the narrowerportion 1448 is displaced toward the axis 1408 so that the inner profile1444 is captured beneath the shoulder 1420 of the radial boss 1418 onthe coupling member 1402 to retain the handle on the coupling member1402. When the button is pressed inwardly to the second position, thewider portion 1446 is displaced toward the axis 1408 so that the widerportion 1446 provides clearance for the handle 1432 to be removed overthe boss 1418. The proximal taper of the boss 1418 allows the handle tobe pressed onto the coupling member 1402 without the need to depress thebutton. The taper of the boss 1418 engages the narrower portion 1448 ofthe button inner profile 1444 causing it to translate into the secondposition as the handle moves distally. Eventually, as the handle seatson the coupling member, the inner profile 1444 passes over the shoulder1420 and the spring causes the button to snap back to the first, locked,position. An alignment mark in the form of an alignment notch 1452 nearthe distal end of the handle 1432 and oriented parallel to thelongitudinal axis 1408 can be aligned with the similar alignment notch1428 on the coupling member 1402 to provide a visual aid for initiallyaligning the handle and coupling member. The proximal end of the handle1432 includes a thread 1454 engageable with the cap 1434. The capprevents unintentional release of the flexible screw. In theillustrative example of FIG. 29, the cap covers the hex head 1482 andprevents unintentional rotation of the draw bar.

A cross pinning guide assembly 1458 is identical to the handle assembly1430 with the addition of a cross pinning guide 1460 extending distallyfrom the handle 1462. In the case of implants having one or morepreformed transverse passages, the cross pinning guide 1460 includesguide holes 1464 having axes that align with the axes of the passages181, 183 when the implant 170 and the cross pinning guide are coupled tothe coupling member 1402. In the case of an implant such as the implant100 of FIGS. 1-4 that does not have a preformed transverse passage,cross fixation may be inserted directly through the implant 100 forminga transverse passage intraoperatively.

A compression sleeve 1466 includes a proximal end 1468 threadablyengageable with the thread 1426 of the hub 1410. The compression sleeve1466 tapers distally and is coaxial with the shaft 1422. The enlargedproximal end of the compression sleeve 1466 supports a large threadcapable of sustaining large axial loads while the narrowed distal end ofthe compression sleeve 1466 will fit through a narrow incision to abutbone adjacent an entry point for the implant into the bone. The threadedengagement of the compression sleeve 1466 with the hub 1410 translatesrotation of the compression sleeve 1466 about the axis 1408 into axialtranslation of the sleeve relative to the shaft 1422. The compressionsleeve 1466 may be a two-part assembly 1467 so that the bone contactingdistal end remains stationary while the threaded portion is rotated. Forexample, the distal end could be shaped to conform to the bone surfacewhile the proximal end rotates to drive the sleeve toward the bone. Forexample, a separate sleeve may have a chamfered tip 1469.

FIG. 35 illustrates an alternative inserter assembly 1300 similar tothat of FIG. 29. The assembly includes an inserter 1302, alternativecross pinning guides 1304, 1306, a compression sleeve 1308 and a cap1310. The inserter includes a handle 1312, a shaft 1314, an implantengagement end 1316, and a drawbar 1318. The shaft has an implantengagement portion at its distal end for engaging a an implant to rotatethe implant into a bone. The drawbar has a threaded tip 1320 and a knob1322 for rotating the draw bar relative to the shaft to engage anddisengage the threaded tip with an implant having a correspondingthreaded hole. The shaft 1314 includes opposed flats 1315 forming anarrow portion 1317. A hole 1319 is formed in the shaft distal to thenarrow portion.

The compression sleeve 1308 is engageable with the inserter shaft 1314in rotating and axial sliding relationship. The distal end 1324 of thecompression sleeve is chamfered to engage a bone surface. Thecompression sleeve 1308 may be provided in different lengths and tipgeometries to fit differently shaped bone surfaces.

A first cross pinning guide 1304 includes a pair of guide holes 1326that align with a corresponding pair of passages in an implant such asfor example implant 270 of FIG. 14. A second, alternative cross pinningguide 1306 includes a pair of holes 1330, a third hole 1332 co-planarwith the pair of holes 1330, and a fourth hole 1334 angularly offsetfrom the others which holes correspond to passages in an implant such asfor example implant 600 of FIG. 22. The cross pinning guides may beprovided in any configuration corresponding to an implant in order toguide placement of cross pins or screws into passages of the implant. Inthe example of FIG. 35, the cross pinning guides include an inserterengaging portion 1340 with an axial passage 1342 and a slot 1344communicating from the passage through a sidewall of the inserterengaging portion 1340. A spring loaded plunger 1345 is retained in aninternal passage of the inserter engaging portion by a actuator 1346.The actuator may be moved by a user against spring pressure to move theplunger from a first position in which the plunger extends into thepassage 1342 and a second, retracted position in which the plungerextends less or not at all into the passage 1342. In use, the crosspinning guide 1304 or 1306 is engaged with the inserter by sliding theinserter engaging portion 1340 over the narrow portion 1317 of the shaftso that the narrow portion passes through the slot 1344 and into thepassage 1342. Pressing downwardly on the cross pinning guide will forcethe plunger 1345 to retract as it is pressed against the top of theshaft. Alternatively, the actuator 1346 may be moved by a user toretract the plunger to ease engagement. Once the cross pinning guide isengaged with the narrow portion of the shaft, it may be slid forwardpast the narrow portion to trap the cross pinning guide radially on theshaft. The plunger will snap into the hole 1319 in the shaft to lock thecross pinning guide axially and rotationally on the shaft. Once locked,the cross pinning guide and inserter are indexed with the guide holes inthe cross pinning guide in known location relative to the inserter shaftand therefore relative to an implant attached to the inserter shaft. Toremove the cross pinning guide from the inserter, the actuator 1346 maybe moved to retract the plunger and then the cross pinning guide may beslid rearwardly to the narrow portion of the shaft at which point thecross pinning guide may be moved radially away from the shaft. The cap1310 may optionally be used to cover the drawbar knob 1322 to allowstriking the handle while preventing damage to or rotation of the knob1322.

FIG. 36 depicts a pair of nesting sleeves including an inner sleeve 1488and an outer sleeve 1489. The inner sleeve 1488 includes a longitudinalpassage sized to guide a drill wire, e.g. a K-wire having a diametersuitable for drilling a pilot hole for a self-tapping screw. The outersleeve 1489 includes a longitudinal passage sized to pass a bone screw.The inner sleeve has an outer diameter that is a slip fit within theouter sleeve. The outer sleeve has an outer diameter that is a slip fitwithin the guide holes of the cross pinning guides 1460, 1304, or 1306.

FIG. 37 depicts a drill wire 1490 receivable in slip fit relationshipwithin the inner sleeve 1488 and having a diameter suitable for drillinga pilot hole for a self-tapping screw. FIG. 38 depicts a depth gauge1492 having an inner passage sized to receive the drill wire 1490 inslip fit relationship and a scale 1493 that indicates the length of thedrill wire 1490 that extends from the gauge 1492 distal end.

FIG. 39 depicts a cannulated rigid drill or reamer 1475 having a reaminghead 1476 at a distal end a rigid shaft 1477 extending proximally fromthe reaming head 1476 to a proximal end 1478. Index marks 1479 on theshaft 1477 may be read adjacent an opening in a bone to indicate anappropriate length of implant for a particular reamed depth. In theillustrative example of FIG. 39, the index marks correspond to implantshaving variable length proximal portions and constant length distalportions. The reaming head 1476 preferably has a length of 10-30 mm soit can be viewed via fluoroscopy and used as a gauge for drilling aspecified minimum distance across a fracture site. In the illustrativeexample of FIG. 39, the reaming head 1476 has a length of 15 mm toclearly indicate when a minimum depth of 15 mm past the fracture sitehas been reached. The reaming head 1476 has a diameter equal to orgreater than the proximal portion of the flexible implant 100, 170. Inthe case of a set of screws as shown in the illustrative example ofFIGS. 5-7 a corresponding set of rigid reamers is provided havingreaming diameters equal to or slightly larger than the proximaldiameters 148, 158, 168 of the screws 140, 150, 160.

FIG. 40 depicts a cannulated flexible drill or reamer 1470 having areaming head 1471 at a distal end, a driver engagement portion at aproximal end 1472 and a flexible shaft 1473 intermediate the reaminghead 1471 and proximal end 1472. In the illustrative example of FIG. 40,the flexible shaft 1473 is joined to the reaming head 1471 and extendsproximally part way toward the proximal end 1472. A rigid shaft 1474extends from the flexible shaft 1473 to the proximal end 1472. Theflexible shaft 1473 may include a variety of flexible constructs as isknown in the art such as, for example, twisted cables, helical cuttubes, interlocking tongue and groove segments, and other flexibleconstructs. In the illustrative example of FIG. 40, the flexible shaft1473 includes a twisted cable construction with an inner cable twistedin a first direction and an outer cable twisted in an opposite directionto provide torque transmitting capability in both rotational directions.The reaming head 1471 has a diameter sized to form a pilot hole for aself-tapping screw or for a tap. The reaming head diameter is preferablyequal to or slightly larger than the minor diameter of the screw thread112, 194 of the implant 100, 170 or the minor diameter of the tap. Aflexible reamer is provided for each minor diameter to be accommodated.In the case of a set of screws like the illustrative example of FIGS.5-7 having a constant minor diameter across screw sizes, only a singleflexible reamer is needed.

FIGS. 41 and 42 depict a centering guide 1494 having a handle 1495 and acannulated end 1496 having an inner passage sized to receive theflexible reamer 1470 in slip fit relationship. The handle 1495, includesa wrench 1497 that may be used, for example, to engage anotherinstrument to provide counter torque.

FIGS. 43-50 depict illustrative examples of a flexible tap 1500according to the present invention. The tap 1500 is capable of forming athread along a straight or curved path. For example, the tap 1500 iscapable of forming a thread along a curved path in a bone to receive athreaded component. In the illustrative example of FIGS. 43-50, the tapis sized to form a thread to receive one of the flexible implants of theillustrative examples of FIG. 1, 8, 12, 16, 18, or 22. Where multiplesizes of screw thread are provided, a set of multiple taps ofcorresponding thread sizes may be provided. The tap may serve as a trialimplant and provides tactile feedback regarding the fit of the implantin the bone. If it is determined that a larger screw is desirable,subsequent larger rigid reamers may be used to re-drill the lateralstraight portion and subsequent larger flexible taps may be used toincrease the distal thread major diameter without having to re-ream themedial curved portion of the bone hole.

The tap 1500 includes a first member 1502 and a second member 1504engaged with the first member 1502. The first member 1502 can berotationally driven relative to the second member so that the firstmember advances a predetermined amount with each full rotation of thefirst member 1502. The first member includes a thread forming portionthat forms a thread in a bone as it is advanced relative to the secondmember. At least a portion of the first member 1502 is flexible so thatthe cutting portion can follow a curved path in the bone.

In the illustrative example of FIGS. 43-50, the first member 1502includes a tap head 1506 having a generally cylindrical body 1508. Thebody 1508 includes a pair of opposing lands 1510 and intervening flutes1512 having a flute depth 1513. A screw thread segment projects fromeach land 1510 to form a tooth 1514 having a tooth face 1519. The tooth1514 is adapted to form a thread in bone. The tooth 1514 may deform orcut the bone to form the thread. In the illustrative example of FIGS.43-50, the tooth 1514 is adapted to cut a thread in a bone. The face1519 is angled away from a radial reference line toward the center ofthe tap head to create a positive rake angle 1516. The face 1519projects a desired thread profile for that tooth to form into the bone.The tap head 1506 may have a single tooth operable to single point cut aspiral thread in the bone as the tap head is rotated. Alternatively, thetap head 1506 can have a two or more teeth such as shown in theillustrative example of FIGS. 43-50. However, the tap head 1506 isintended to be able to follow a curved path in a bone. As the tap head1506 follows a curved path to form a thread about the path axis, thepitch of the thread so formed will vary from a minimum on the inside ofthe curve to a maximum on the outside of the curve. With an increasingnumber of teeth 1514, and especially as the number of thread segmentsalong the length of the tap head 1506 is increased, the tap head 1506becomes more constrained. Driving a tap head with a large number ofteeth along a curved path will result in damage to the formed bonethread due to e.g. the trailing teeth interfering with the bone threadas the leading teeth cause the tap head to tilt to follow the curvedpath. A single tooth provides the least constraint and the greatest easein following a curved path. Two teeth, as in the illustrative example ofFIGS. 43-50, may help balance the loads on the tap head while stillallowing sufficient maneuverability to produce a well formed thread.Also, with two teeth, the leading tooth may project a shorter distance1518 from the land 1510 so that a portion of the thread depth is removedby the first tooth and another portion is removed by the second tooth toreduce the torque required to drive the tap. When used to tap apre-drilled hole, the land, or lands, fit within the hole and guide thetap head 1506 along the hole while the teeth 1514 cut the thread intothe bone.

In the illustrative example of FIGS. 43-50, the first member 1502further includes an elongated flexible shaft 1520 having a first end1522 connected to the tap head 1506 and a second end 1524 opposite thefirst end. The flexible shaft 1520 may include a variety of flexibleconstructs as is known in the art such as, for example, twisted cables,helical cut tubes, interlocking tongue and groove segments, and otherflexible constructs. In the illustrative example of FIGS. 43-50, theflexible shaft 1520 includes a twisted cable construction with an innercable twisted in a first direction and an outer cable twisted in anopposite direction to provide torque transmitting capability in bothrotational directions.

In the illustrative example of FIGS. 43-50, the first member furtherincludes a driving shaft 1530 having a first end 1532 connected to thesecond end 1524 of the flexible shaft and a second end 1534 opposite thefirst end 1532. The driving shaft 1530 includes a helical thread 1536having a thread pitch 1538. In the illustrative example of FIGS. 43-50,the thread 1536 is a multi-lead thread so there are two separate threadflights 1537, 1539 intertwined along the driving shaft 1530 and thethread pitch 1538 of each thread flight is measured as shown atreference numeral 1538. The thread pitch 1538 is the distance thedriving shaft 1530 will translate along its axis for each completerevolution of the driving shaft 1530. Where the tap head 1506 includesmultiple teeth 1514, the teeth are spaced longitudinally a distancecorresponding to the driving shaft thread pitch 1538. Preferably thedriving shaft is rigid. Also preferably, the second end 1534 includes anengagement portion releasably engageable with a driver. A driver may bea handle to provide a grip for manually turning by a user or a drivermay be a rotary mechanism such as a powered drill.

In the illustrative example of FIGS. 43-50, the second member 1504 isthreadably engaged with the thread 1536 of the driving shaft 1530 suchthat rotating the driving shaft 1530 relative to the second member 1504translates the driving shaft 1530 and consequently the flexible shaft1520 and tap head 1506 a distance equal to the thread pitch 1538 witheach revolution of the drive shaft 1530. The tap head 1506 will form athread in a bone with a pitch equal to the driving shaft thread pitch1538. Changing the driving shaft thread pitch 1538 will change theformed bone thread pitch to a corresponding value. In the illustrativeexample of FIGS. 43-50, the second member 1504 is an anchor member ableto be anchored to a bone and includes a hollow shaft 1540 having a firstend 1542 and a second end 1544 opposite the first end. The first end1542 defines a bone engagement portion having an anchor feature thatgrips the bone to secure the second member 1504 against axialtranslation relative to the bone as the drive shaft 1530 is rotated andthe bone is threaded. In other words the anchor feature provides acounterforce to allow the threaded engagement between the first andsecond members to drive the tap head 1506 into the bone. The anchorfeature may include barbs, threads, pins, screws, expandable members andother suitable features for securing a member to a bone. In theillustrative example of FIGS. 43-50, the anchor feature includes aself-tapping thread 1546 formed on the first end 1542 of the shaft 1540.The second end 1544 of the shaft is joined to a hub 1548 having athreaded passage 1550 (FIG. 49) engaged with the thread 1536 of thedriving shaft 1530. A knob 1552 is mounted to the hub 1548 tofacilitated engaging the self-tapping thread 1546 with a bone.

Alternatively, as shown in FIG. 44, a driver engagement 1553 may besubstituted for the knob 1552 to permit engagement with a powered driveror modular handle. For example, a quick release handle may be engagedwith the engagement 1553 to turn the self-tapping thread 1546 into abone and then removed. Preferably, such a handle will cover the end 1534of the first member to prevent accidental driving of the driving shaft1530 when the self-tapping thread 1546 is turned into a bone. Inaddition, a wrench may be engaged with the driver engagement 1553 toprovide counter torque when the driving shaft is driven. For example,the wrench 1497 of the centering guide 1494 may be used to provide acounter torque on the second member when the driving shaft 1530 of thefirst member is rotated relative to the second member.

FIGS. 49 and 50 are partial sectional views depicting the second member1504 in cross section and the first member 1502 in orthographicprojection to show the interaction between the two. As seen in FIG. 49,the thread 1536 is engaged with the passage 1550. In FIG. 50, thedriving shaft 1530 has been rotated four revolutions to advance thedriving shaft 1530, flexible shaft 1520, and tap head 1506 four pitchlengths relative to the second member 1504. An index mark 1541, orshoulder or other feature, is provided on the driving shaft 1530 toindicate when the tap head has been driven to a depth sufficient toreceive the distal end of the flexible implant. When the mark 1541 isaligned with the back edge of the knob 1552, the tap head has beendriven to a sufficient depth.

FIGS. 51 and 52 depict an illustrative example of a method of forming athread in a bone 1560 using the tap 1500 of FIGS. 43-50. A path for thetap 1500 is defined in the bone 1560. The path may be defined by anatural bone feature such as an intramedullary canal. The path may bedefined by introducing a guide wire in the bone and the tap 1500 may becannulated to follow the guide wire. The path may be defined by forminga hole 1562 in the bone 1560 as shown in the illustrative example ofFIGS. 51 and 52. The path may be straight or curved and the tap 1500 maybe used for tapping straight or curved holes. However, the tap 1500 isparticularly useful for forming a thread in curved holes thattraditional rigid taps are incapable of tapping. In the illustrativeexample of FIGS. 51 and 52, the hole is curved such as might be producedby flexibly reaming an intramedullary canal of a bone such as aclavicle, rib, fibular, radius, metatarsal, metacarpal or other bone.

In FIG. 51, the tap is engaged with the hole 1562 by turning the anchorfeature of the second member 1504 into the hole 1562.

In FIG. 52, the driving shaft 1530 has been rotated several revolutionsto advance the tap head 1506 into the bone hole to form a thread in thebone having a pitch equal to the driving shaft thread pitch 1538. Whilethe driving shaft 1530 is preferably rigid and advances linearlyrelative to the second member 1504, the flexible shaft 1520 bends sothat the tap head 1506 may follow any curvature in the path defined inthe bone.

FIGS. 53-72 depict an illustrative method of using the implant 170 ofFIG. 8 and the instruments of FIGS. 29-34 and FIGS. 36-50 to fix afractured clavicle 1600. The patient is positioned for ready access tothe surgical site. For example, the patient may be placed in a supine orbeach chair position. A C-arm is positioned to enable anterior-posterior(AP) and cephalic views of the operative site. A 2-3 cm incision is madeat the fracture site, e.g. along Langer's Lines, running perpendicularto the long axis of the clavicle to expose the fracture site. Theplatysma muscle is freed from the skin and split between its fibers. Themiddle branch of the supraclavicular nerve is identified and retracted.

Referring to FIG. 53, the medial end 1602 of the lateral fragment 1604of the fractured clavicle is elevated from the fracture site incision. AK-wire 1606 (or pin or drill) is drilled into the medial end of thelateral fragment 1604 and advanced through the dorsolateral cortex 1608and out through the skin. Preferably, the K-wire is placed as farposteriorly in the lateral fragment 1604 as is possible to facilitatelater steps in the procedure. Referring to FIG. 54, the rigid reamer1475 is connected to a driver (not shown) and guided over the K-wire toream the lateral fragment 1604 from medial to lateral. The rigid reamer1475 is replaced with a larger rigid reamer, if necessary, andsequential reaming is carried out until a desirable engagement isachieved, e.g. cortical engagement. The rigid reamer extends through thelateral cortical wall of the lateral fragment to create a lateralopening 1610 into the reamed bone tunnel 1612. The markings on thereamer shaft may be configured to indicate an appropriate implant lengthto reach the fracture. In such case, the length is noted. Alternatively,the reference numbers may be configured so that the measurement is takenduring lateral-to-medial drilling as shown in FIG. 55.

Referring to FIG. 55, the rigid reamer 1475 is removed from the lateralfragment 1604 and reversed so that it can be directed from lateral tomedial through the bone tunnel 1612. To facilitate location of theopening 1610, the reamer may be passed retrograde, medial to lateral,through the tunnel 1612 and through the skin and then reconnected to thedriver. Alternatively, the rigid reamer 1475 may be passed laterally tomedially into the tunnel 1612. Alternatively, a guide wire may be placedto guide the reamer. For example, after the previous step, shown in FIG.54, a guidewire may be advanced through the tunnel in the lateralfragment as the reamer is removed. The fracture may be reduced and theguide wire advanced into the medial fragment. The reamer may then beengaged with the guide wire for lateral-to-medial reaming.

With the rigid reamer 1475 in the tunnel 1612 and the fracture reducedso that the lateral fragment 1604 and medial fragment 1614 are abutting,the rigid reamer is advanced across the fracture 1624 and into themedial fragment 1614 creating an initial medial bone tunnel 1616.Preferably the reamer is advanced a sufficient distance to ensure that anon-threaded portion of the implant 100, 170 proximal to the distalthread 112, 194 will be positioned across the fracture since thenon-threaded portion is more fatigue resistant than the threadedportion. Preferably the reamer is advanced a minimum of 15 mm into themedial fragment. In the illustrative example of FIGS. 53-72, the reaminghead 1476 of the rigid reamer 1475 is 15 mm long and serves as a visualcue of the reamer depth when viewed radiographically. At this point thereference marks 1479 on the reamer may be read to indicate theappropriate size of flexible screw. Alternatively, the reference marksmay be configured so that the measurement is taken duringmedial-to-lateral reaming of the lateral fragment as shown in FIG. 54.

Referring to FIG. 56, the medial and lateral fragments 1614, 1604 aredisplaced and a flexible guide wire 1620 is inserted into the initialmedial tunnel 1616 and further into the medial fragment 1614 to define apath. Optionally, a centering guide like the centering guide 1494 butsized for the flexible guide wire may be used to center the guide wire1620 in the initial medial tunnel 1616. Once started, the guide wire1620 will tend to follow the cortical wall of the bone. Since theclavicle has a curved shaft, the guide wire 1620 will form a curvedpath.

Referring to FIG. 57, the centering guide 1494 is inserted into theinitial medial tunnel 1616 and the flexible reamer 1470 is inserted overthe guide wire 1620, through the centering guide 1494 and into contactwith the medial fragment 1614. The centering guide 1494 is optional buthelps to center the reaming head 1471 of the flexible reamer 1470 in theinitial medial tunnel 1616.

Referring to FIG. 58, the flexible reamer 1470 has been advanced overthe guide wire 1620 to form a medial fragment bone tunnel. For example,a powered driver may be connected to the flexible reamer to drive itinto the medial fragment.

Referring to FIG. 59, the flexible reamer 1470, guidewire 1620 andcentering guide 1494 have been removed and the flexible tap 1500 isengaged with the initial medial tunnel.

Referring to FIG. 60, the tap head 1506 has been advanced by rotatingthe drive shaft 1530 relative to the second member 1504 to form ahelical thread in the medial fragment bone tunnel, for example byattaching a handle to the driving shaft and rotating the handle andshaft together. If necessary, the knob 1552 may be used to apply countertorque as the driving shaft 1530 is rotated. The tap may serve as atrial implant and provides tactile feedback regarding the fit of theimplant in the bone. If it is determined that a larger screw isdesirable, a subsequent larger rigid reamer may be used to re-drill thelateral straight portion and a subsequent larger flexible tap may beused to increase the distal thread major diameter without having tore-ream the medial curved portion of the bone hole. The tap head 1506 isadvanced until the index mark 1541 is aligned with the back side of theknob 1552. If an implant with a proximal threaded portion is used, suchas implant 100 of FIGS. 1-4, a lateral tap may be used to tap thelateral bone fragment to receive the proximal thread.

Referring to FIG. 61, the tap 1500 has been removed and the fracturereduced so that the lateral fragment 1604 and medial fragment 1614 areabutting.

Referring to FIG. 62, an optional guide wire 1622 has been insertedlateral to medial through the lateral bone tunnel 1612 and across thefracture to aid in guiding the implant 170 across the fracture. Noguidewire would be used for an implant that is not cannulated. In thisexample, the cannulated implant 170 of FIG. 8 will be used with a guidewire.

Referring to FIG. 63, the implant 170 corresponding to the last tap sizeused has been coupled to the inserter 1400 and advanced over the guidewire 1622, through the lateral bone tunnel 1612 and into the medial bonetunnel. In the illustrative example of FIG. 63, the fracture 1624 isshown slightly displaced as might happen during the procedure and toillustrate how the inserter 1400 may be used to reduce the fracture.

Referring to FIG. 64, the implant 170 has been advanced further so thatthe thread 194 of the flexible distal portion engages the thread in themedial fragment 1614. The screw is advanced until it is fully seated inthe prepared thread in the medial bone fragment. Optionally, the implant100 may be axially driven with a mallet through the lateral bonefragment until just short of the distal thread engagement. The screw maythen be threaded into full engagement with the prepared thread in themedial fragment.

Referring to FIG. 65, the compression sleeve 1466 has been rotatedrelative to the hub 1410 so that the threaded engagement between themcauses the compression sleeve 1466 to press against the lateral bonefragment 1604 and the hub 1410 to move away from the compression sleeve.The draw bar 1480 (FIG. 17) moves with the hub since the head 1482 ofthe draw bar abuts the proximal end of the post 1416. The interaction ofthe hub 1410 with the compression sleeve 1466 and the compression sleeve1466 with the bone pulls the implant 170 laterally. Since the screw isanchored in the medial fragment 1614 and can slide in the lateralfragment 1604, this interaction applies compression to the fracture1624.

Referring to FIG. 66, the handle assembly 1430 is removed from the hub1410 in preparation for attaching the cross pinning guide assembly 1458.

Referring to FIG. 67, the cross pinning guide assembly 1458 has beenengaged with the hub 1410. With the cross pinning guide assembly 1458locked onto the hub, guide holes 1464 are aligned with the passages 181,183 in the proximal end of the implant 170.

Referring to FIG. 68, the inner sleeve 1488 and outer sleeve 1489 aresequentially nested in the guide holes 1464 (shown positioned in oneguide hole 1464 in FIG. 68) and used to guide a drill wire 1490 into thebone and through each of the passages 181, 183. Through tactile feedbackthe user can detect when the drill wire 1490 is engaged with the farcortical wall of the bone fragment. For example, the drill wire 1490 maybe guided through the guide sleeves, through the near cortex, through apassage in the screw, and into the far cortex of the lateral bonefragment. If wire cross fixation is adequate, the cross fixation guidemay be removed and the wire may be trimmed flush with the bone surface.

However, if screw cross fixation is desired, additional steps may beperformed. For example, if desired, an optional counter sink tool (notshown) may be placed over the drill wire 1490 and used to counter sinkthe bone surface to receive a screw head. The inner sleeve 1488 may beremoved and the depth gauge 1492 may be inserted over the drill wire andthrough the outer sleeve 1489 until it contacts the bone. Theappropriate screw length is then read by comparing the proximal end ofthe drill wire 1490 to the scale 1493 on the depth gauge 1492.

Referring to FIG. 69, a self-tapping cross-fixation screw 1626 has beeninserted through the outer sleeve 1489 and turned into the bone so thatit extends through the flexible implant 170. Following these same steps,as many additional cross fixation screws 1626 may be inserted throughthe flexible implant 170 as there are passages in the implant 170.

Referring to FIG. 70, the cap 1434 has been removed from the crosspinning guide assembly 1458 to expose the head 1482 of the draw bar.Alternatively, the entire cross pinning guide assembly 1458 may beremoved to expose the head 1482.

Referring to FIG. 71, the draw bar 1480 is rotated to unscrew it fromthe implant 170 and detach the inserter assembly 1400 from the implant170.

Referring to FIG. 72, the final fixation construct is shown with thefracture 1624 compressed, the implant 170 engaged with the medial bonefragment 1614, and cross fixation screws 1626 locking the implant 170 inthe lateral fragment 1604.

FIGS. 73-81 depict an illustrative method of using the implant 600 ofFIG. 22 and the inserter assembly 1300 of FIG. 35 to fixate a fracturedfibula.

Referring to FIG. 73, a fibula 1700 having a fracture 1702 is fixated byfirst reducing the fracture such as for example with bone forceps. Anincision is made across the end of the lateral malleolus 1704 centeredwith the long axis of the fibular shaft. A pin or drill may be used topierce the fibular cortex and establish the implant insertiontrajectory. For example, a K-wire may be inserted through the fibularcortex between the anterior talofibular ligament (ATFL) and thecalcaneofibular ligament (CFL). A flexible awl 1706, for example a Rushawl reamer, may be inserted through the hole formed in the cortex tocreate a path along the curved intramedullary canal of the fibula.

Referring to FIG. 74, the awl 1706 has been removed and a K-wire 1708inserted along the implant insertion path. A rigid reamer 1710 is drivenover the K-wire to create the entry portal to a desired depth. Forexample, if the implant is provided in a choice of discrete bodylengths, the reamer is driven to a depth corresponding to one of thoselengths. Preferably, the depth is chosen such that the implant proximalportion will span the fracture 1702.

The implant path is then tapped. In first tapping example, shown inFIGS. 75 and 76, the tap 1500 is used. Referring to FIG. 75, the tap1500, with the alternative driver engagement 1553 of FIG. 44, is engagedwith a first handle 1712. The tap is anchored in the lateral malleolusby turning the self-tapping thread 1546 into the hole formed with therigid reamer 1710. The first handle 1712 covers the end 1534 of thedriving shaft 153 of the tap so that the tap head 1506 is not advancedinadvertently. Referring to FIG. 76, the first handle 1712 is removedand a second handle 1714 is engaged with the end 1534 of the drivingshaft 1530 and rotated to tap the implant path. A wrench, such as wrench1497 of FIG. 42 may be engaged with the driver engagement 1553 to applycounter torque if desired. Alternatively, in a second tapping exampleshow in FIG. 77, a one-piece tap 1720 may be used since the fibularintramedullary canal has a relatively subtle curvature The tap 1720 inthe example of FIG. 77, has a cutting thread form corresponding to thethread form of the implant 600 of FIG. 22. The minor diameter and pitchof the tap 1720, like the implant 600, are such that the tap can flex tofollow the fibular curvature.

Referring to FIG. 78, the inserter 1302 is joined to the implant 600 byinserting the implant engagement end 1316 into the drive socket of theimplant 600 and turning the knob 1322 to thread the drawbar into thethreaded hole in the end of the drive socket to draw the implant intoengagement with the inserter and secure it in place. Optionally, acompression sleeve 1724 may first be placed over the inserter shaft. Inthe example of FIG. 78, the compression sleeve has a flat distal endsince it will be abutting the distal end of the fibula and no chamfer isnecessary to provide sufficient bearing contact with the bone.Optionally, the cap 1310 may be placed over the handle 1312 of theinserter if it is desired to impact the implant 600 along the initialportion of its insertion path.

Referring to FIG. 79, the implant 600 has been threaded into the fibula1700 until the compression sleeve contacts the lateral malleolus at thedistal end of the fibula. With the compression sleeve 1724 bearing onthe bone, further rotation of the implant causes the bone fragments tobe pressed together to reduce the fracture 1702. Preferably, the implantis advanced until it is 2-5 mm below the surface of the lateralmalleolus.

Referring to FIG. 80, the cross pinning guide 1306 corresponding to theimplant 600 is mounted to the inserter 1302 and the inserter 1302, crosspinning guide 1306 and implant 600 are rotated to align the guide holes1330, 1332, 1334 with the desired screw trajectories. Small stabincisions are created at each screw entry point to allow the drillsleeve 1488 to seat against the bone surface. A screw is installed inthe bone and intersecting each transverse hole in the implant 600 byinserting the drill sleeve 1488 in each guide hole, guiding a drillthrough the bone and transverse hole, using the depth gage to measureproper screw length, countersinking the bone surface, and screwing thescrew into the bone with the screw traversing the transverse hole. Thisis repeated for each desired screw.

Referring to FIG. 81, screws placed through the first pair of transverseholes 606 may be used to attach bone fragments such as the lateralmalleolus 1704 to the fibular shaft 1700. Screws placed through thesecond pair of transverse holes 612 may be extended through the fibulaand into the tibia 1726 to reinforce the syndesmosis joint. Theimplants, instruments, and methods according to examples of theinvention may be used to fixate bones, bone fragments and jointthroughout the body.

Referring to FIG. 82, the implant 170 of FIG. 8 is used to repair anolecranon fracture of an ulna 1740 having a fracture 1742 and a fragment1744. The implant 170 is inserted through the fragment 1744 into theintramedullary canal of the ulna 1740. As the implant is rotated, thedistal threaded portion engages the bone and pulls the proximal portioninto the bone to a position bridging the fracture 722. The distalthreaded portion bends to follow the curved path of the intramedullarycanal. Bone screws are placed into the fragment and the holes of theimplant 170 to secure the fragment.

Referring to FIG. 83, the implant 170 of FIG. 8 is used to repair aJones fracture of a fifth metatarsal 1750 having a fracture 1752 and afragment 1754. The implant 170 is inserted through the fragment 1754into the intramedullary canal of the fifth metatarsal. As the implant isrotated, the distal threaded portion engages the bone and pulls theproximal portion into the bone to a position bridging the fracture 1752.The distal threaded portion bends to follow the curved path of theintramedullary canal. Bone screws are placed into the fragment and theholes of the implant 170 to secure the fragment.

Various illustrative examples have been described. The various examplesmay be substituted and combined and other alterations made within thescope of the invention.

What is claimed is:
 1. A method of fixating a first bone portionrelative to a second bone portion, the method comprising: advancing arigid drill to form a first bone hole from an outer surface of the firstbone portion to a fracture site interposed between the first and secondbone portions; advancing the rigid drill across the fracture site toform a second bone hole into the other one of the medial and lateralbone fragments; engaging a flexible drill with the second bone hole; andadvancing the flexible drill to extend the second bone hole along acurved path.
 2. The method of claim 1 further comprising: advancing aflexible tap in the second bone hole to form a helical thread along thecurved path.
 3. The method of claim 1 further comprising: driving aflexible threaded implant through the first bone hole, across thefracture site and into the second bone hole so that the threaded portionextends along the curved path.
 4. The method of claim 3 furthercomprising: compressing the first and second bone portions together. 5.The method of claim 4 wherein compressing the first and second boneportions together comprises pulling on the flexible threaded implantwhile pressing on a bone surface adjacent the first bone hole.
 6. Themethod of claim 4 wherein compressing the first and second bone portionstogether comprises coupling the flexible threaded implant to a driver inaxial force and torque transmitting relationship, abutting a portion ofthe driver against the first bone, and rotating the flexible threadedimplant.
 7. The method of claim 5 further comprising: displacing asleeve coupled to a portion of the driver so that the sleeve pressesagainst the bone surface adjacent the first bone hole.
 8. The method ofclaim 7 wherein the sleeve threadably engages the driver, the methodfurther comprising: rotating the sleeve to threadably drive the sleevein a first direction and pull the flexible threaded implant in a secondopposite direction.
 9. The method of claim 3 further comprising: placinga fixation element transversely through the flexible threaded implantand into at least one of the medial and lateral bone fragments.
 10. Themethod of claim 9 wherein placing a fixation element comprises placingthe fixation element through a passage formed in a non-threaded firstportion of the flexible threaded implant, the first portion beingpositioned within the first bone hole.
 11. The method of claim 9 whereinplacing a fixation element comprises engaging a modular guide assemblywith the driver while the driver remains engaged with the flexiblethreaded implant and guiding the fixation element with the guideassembly.
 12. The method of claim 9 wherein placing a fixation elementcomprises: engaging a modular guide assembly with the driver while thedriver remains engaged with the flexible threaded implant; guiding ahole forming instrument with the modular guide through a passage formedin a non-threaded first portion of the flexible threaded implant, thefirst portion being positioned within the first bone hole; inserting ascrew through the passage while the modular guide assembly remainsengaged with the driver and the driver remains engaged with the flexiblethreaded implant.
 13. The method of claim 3 wherein the first and secondbone portions are medial and lateral fragments of a fractured clavicle,the method comprising inserting the flexible threaded implant so that adistal threaded portion of the implant is engaged with theintramedullary canal of the medial fragment and an unthreaded portion ofthe implant spans the fracture.
 14. The method of claim 3 wherein thefirst and second bone portions are a lateral malleolus and shaft of afractured fibula, the method comprising inserting the flexible threadedimplant so that a distal threaded portion of the implant is engaged withthe intramedullary canal of the fibular shaft and an unthreaded portionof the implant spans the fracture.
 15. The method of claim 14 furthercomprising: inserting a first fixation member into a transverse passagethrough a portion of the flexible threaded implant lying within thelateral malleolus, the fixation member extending into the lateralmalleoulus on opposite sides of the flexible threaded implant.
 16. Themethod of claim 15 further comprising: inserting a second fixationmember into a transverse passage through a portion of the flexiblethreaded implant, the second fixation member extending into the fibulaon a first side of the flexible threaded implant and the second fixationmember extending into a tibia on a second side of the flexible threadedimplant opposite the first side.
 17. The method of claim 3 wherein thefirst and second bone portions are an olecranon and shaft of a fracturedulna, the method comprising inserting the flexible threaded implant sothat a distal threaded portion of the implant is engaged with theintramedullary canal of the ulnar shaft and an unthreaded portion of theimplant spans the fracture.
 18. The method of claim 3 wherein the firstand second bone portions are proximal and distal fragments of a fracturemetatarsal bone, the method comprising inserting the flexible threadedimplant so that a distal threaded portion of the implant is engaged withthe intramedullary canal of the distal metatarsal shaft and anunthreaded portion of the implant spans the fracture.